Nicholson has faced suspicion about his commitment to the Republican Party given the fact he used to be president of the College Democrats of America and spoke at the 2000 Democratic National Convention.

In a statement to CNN, Nicholson said since his parents are Democrats, it is not surprising that they would contribute to Baldwin’s campaign.

“I’m a conservative today not because I was born one, but because of the experience I earned as a Marine in combat, my experience as a husband and father, my choice to be a Christian, the schools I chose to attend and the decision to pursue the career that I have,” he said. “Regardless of who may disagree with my life decisions, I would not trade these experiences for anything, and they will always guide my views as Wisconsin’s next U.S. Senator.”

Nicholson is currently engaged in a tough primary against state Sen. Leah Vukmir, and his previous views have become fodder for his Republican rival.

Last month, former White House Chief of Staff and Wisconsin GOP Chairman Reince Priebus endorsed Vukmir and cited Nicholson’s old views.

“When you go from president of the College Democrats to wanting to be the U.S. senator for the Republican Party, I think there should be some in-between time,” Priebus said in an interview with WISN-AM 1130.

Republicans are targeting Wisconsin this year after Sen. Ron Johnson won re-election in 2016 and President Donald Trump became the first Republican to win the state since President Ronald Reagan in 1984.